Adipose tissue cultures: During cardiac surgery adipose tissue samples will be collected. In more details subcutaneous adipose tissue will be collected from the site of sternum incision; pericardial adipose tissue will be collected from the site close to right ventricle; and femoral adipose tissue will be collected from the area of saphenous vein harvesting (when available). Adipose tissue samples obtained during surgery will be cultured ex-vivo using a standard adipose tissue protocol.